Mathematical modeling of constructed wetlands for hexavalent chromium removal.

Constructed wetlands (CWs) have been extensively used in Cr(VI) removal and have proven their ability to achieve high removal efficiencies. Although, numerous studies have been published in the past years presenting experimental results of CWs treating wastewater with Cr(VI) concentrations, a mathematical modeling describing the processes for Cr(VI) removal in CWs is lacking. In this work a mathematical model was developed, able to accurately describe the main mechanisms and reactions (i.

Thermally Modified Palygorskite Usage as Adsorbent in Fixed-Bed Reactor for High Concentration NH-N Removal and Further Application as N-Fertilizer in Hydroponic Cultivation.

Palygorskite sample (Pal) underwent thermal treatment at 400 °C (T-Pal) to be used as adsorbent for the removal of 200 mg NH-N/L from artificial solution. After thermal treatment, the sample was characterized via X-ray diffraction (XRD) and scanning electron microscopy (SEM). For NH-N removal, T-Pal was added as a bed matrix in fixed-bed reactor experiments and the effect of flow rate was determined.

Using raw and thermally modified fibrous clay minerals as low concentration NH-N adsorbents.

Raw and modified fibrous clay minerals palygorskite (Pal) and sepiolite (Sep) were tested for their ability to remove ammonium from ammonium polluted water. Palygorskite and sepiolite underwent thermal treatment at 400°C (T-Pal and T-Sep respectively). Raw and thermally treated samples were characterized using XRD, SEM, BET, FTIR, TGA, zeta potential, and XRF.

A Leptolyngbya-based microbial consortium for agro-industrial wastewaters treatment and biodiesel production.

A mixed cyanobacterial-mixotrophic algal population, dominated by the filamentous cyanobacterium Leptolyngbya sp. and the microalga Ochromonas (which contributed to the total photosynthetic population with rates of less than 5%), was studied under non-aseptic conditions for its efficiency to remove organic and inorganic compounds from different types of wastes/wastewaters while simultaneously producing lipids. Second cheese whey, poplar sawdust, and grass hydrolysates were used in lab-scale experiments, in photobioreactors that operated under aerobic conditions with different initial nutrient (C, N and P) concentrations.

A novel horizontal subsurface flow constructed wetland: Reducing area requirements and clogging risk.

The use of Constructed Wetlands (CWs) has been nowadays expanded from municipal to industrial and agro-industrial wastewaters. The main limitations of CWs remain the relatively high area requirements compared to mechanical treatment technologies and the potential occurrence of the clogging phenomenon. This study presents the findings of an innovative CW design where novel materials were used.

Treatment of table olive washing water using trickling filters, constructed wetlands and electrooxidation.

The production of table olives is a significant economic activity in Mediterranean countries. Table olive processing generates large volumes of rinsing water that are characterized by high organic matter and phenol contents. Due to these characteristics, a combination of more than one technology is imperative to ensure efficient treatment with low operational cost.

Mathematical modeling of olive mill waste composting process.

The present study aimed at developing an integrated mathematical model for the composting process of olive mill waste. The multi-component model was developed to simulate the composting of three-phase olive mill solid waste with olive leaves and different materials as bulking agents. The modeling system included heat transfer, organic substrate degradation, oxygen consumption, carbon dioxide production, water content change, and biological processes.

Integrated Cr(VI) removal using constructed wetlands and composting.

The present work was conducted to study integrated chromium removal from aqueous solutions in horizontal subsurface (HSF) constructed wetlands. Two pilot-scale HSF constructed wetlands (CWs) units were built and operated. One unit was planted with common reeds (Phragmites australis) and one was kept unplanted.

Molasses as an efficient low-cost carbon source for biological Cr(VI) removal.

In the present study, indigenous microorganisms from industrial sludge were used to reduce the activity of Cr(VI). Molasses, a by-product of sugar processing, was selected as the carbon source (instead of sugar used in a previous work) as it is a low-cost energy source for bioprocesses. Initially, experiments were carried out in suspended growth batch reactors for Cr(VI) concentrations of 1.

Biological Cr(VI) removal using bio-filters and constructed wetlands.

The bioreduction of hexavalent chromium from aqueous solution was carried out using suspended growth and packed-bed reactors under a draw-fill operating mode, and horizontal subsurface constructed wetlands. Reactors were inoculated with industrial sludge from the Hellenic Aerospace Industry using sugar as substrate. In the suspended growth reactors, the maximum Cr(VI) reduction rate (about 2 mg/L h) was achieved for an initial concentration of 12.